The general purpose of a luer hub is to connect a catheter to some mating piece of equipment such as a syringe, a power injection tube or a manifold. It happens, however, that the luer hub is also used by physicians to control the positioning of the catheter as it is being advanced into the vasculature of a patient. In order for the physician to properly control the catheter during such an advancement, it is necessary to subject the catheter to both axial and rotational forces. A major concern in all of this is that, while the forces which are exerted on the catheter must provide for the desired degree of catheter flexibility and operational control, they can not be allowed to cause the catheter to kink or otherwise become inoperative.
Various types of connecting hubs have been proposed for specialized uses with various types of catheters. For example, U.S. Pat. No. 4,445,893, which issued to Bodicky for an invention entitled "Infusion Apparatus," discloses an intravenous catheter placement device which includes a hub that is attached directly to a rigid cannula. In another example, U.S. Pat. No. 4,875,481, which issued to Higgins for an invention entitled "Catheter with Coiled Wire Attachment," discloses a wire having a coiled proximal end that is positioned in a hub, and an elongated distal end which extends from the hub through the PTCA catheter. The wire in this case is used for steering control over the catheter by rotation of the hub. In yet another example, U.S. Pat. No. 5,167,647, which issued to Wijkamp et al. for an invention entitled "Catheter with a Strain Relief Member," discloses a tubular shaped strain relief member which extends distally from the hub and over a short portion of the catheter. None of these examples, however, teach or suggest a hub and strain relief element which are formed, in combination, as an integral unit, and which provide for a progressive transition from the relative rigidity of the hub to the flexure required by the associated catheter. More recently, however, efforts have been made to address this issue. For example, U.S. application Ser. No. 09/021,682, and U.S. application Ser. No. 09/046,241, which are each assigned to the same assignee as the present invention, both disclose spiral strain relief elements which are designed to provide such a transition, albeit with different structure than disclosed herein for the present invention.
An angiographic catheter, due to the nature of its specific function, can be designed to have a relatively small diameter. Hence, in comparison with infusion catheters, such as PTCA catheters and atherectomy catheters which often require relatively large diameters, the angiographic catheter and other small diameter catheters are particularly susceptible to kinking. It often happens that this problem is most pronounced near the hub where control forces are imparted by the physician to control movement of the catheter into a patients vasculature.
In light of the above, it is an object of the present invention to provide a connector hub which provides the physician with control and sensitivity during the placement of a catheter into the vasculature of a patient. It is another object of the present invention to provide a connector hub for a catheter which will provide for a progressive transition from the relative rigidity of the hub to the flexure required by the catheter. Yet another object of the present invention is to provide a connector hub for a catheter which presents the hub and a strain relief element as an integral unit. Another object of the present invention is to provide a connector hub for a catheter which is ergonomically efficient in providing a physician with control structure for rotating and advancing the catheter into the vasculature of a patient. Still another object of the present invention is to provide a connector hub for a catheter which is easy to manufacture, relatively simple to use and comparatively cost effective.